One type of stationary cardiovascular exercise equipment which has become extremely popular based predominantly upon its low-impact and natural motion is the elliptical exercise machine. A wide variety of elliptical exercise machines have been developed. Briefly, elliptical exercise machines include foot supports supported upon foot links with the foot links pivotally connected at a first end through a linkage system to a drive shaft for travel along a defined closed loop path (e.g., circular, elliptical, oval, etc.) and connected at the other end for reciprocating motion along a defined path as the first end travels along the closed loop path. This combination of looping and reciprocating paths of travel at opposite ends of the foot links impart an “elliptical” type motion to the foot supports attached to the foot links.
Some elliptical exercise machines permit a user to exercise in both a forward and a backward motion. While this feature enhances the value of the machine by permitting a user to employ a completely different motion which emphasizes different muscle and muscle groups, the machines do not alter the path of travel of the foot supports to accommodate the inherent difference in stride between a forward walking/running motion and a backward walking/running motion.
Accordingly, a need exists for elliptical exercise machines which permit a user to exercise in both a forward and a backward motion and alters the path of travel of the foot supports dependant upon whether the user is moving in a forward and backward direction in order to accommodate the inherent difference in stride between a forward walking/running motion and a backward walking/running motion.